1. Field of the Invention
A pinch valve sleeve for reducing the pressure of fluid flowing therethrough.
2. Description of the Prior Art
Pinch valve sleeves are generally tubular and are constructed of a flexible resilient elastomeric material. They are positioned in a valve body which is interprosed in a conduit, duct, pipe or tube, together with means to constrict the sleeve intermediate its ends so as to curtail, terminate, or control the flow of fluid through the conduit or the like. Usually, the valve sleeve is concentrically oriented within an outer rigid valve housing and the sleeve is constricted by suitable means which squeezes the sleeve inwardly to deform or collapse the same and thus provide a smaller fluid flow passage.
Normally, a pinch valve sleeve is made from pure gum rubber, neoprene, Buna, butyl rubber, Hypalon, polyurethane, Viton, Teflon or silicon rubber. Typically, any suitable flexible and resilient material of construction may be employed for the sleeve. However, a synthetic rubber such as Hypalon, Buna, neoprene, an elastomeric plastic, or natural rubber is preferred. Hypalon is a rubbery material obtained by the chlorination and sulfonation of polyethylene. Buna is a rubber substitute prepared by the polymerization of butadiene. Neoprene is polychloroprene made by the polymerization of chloroprene; e.g. neoprene is a generic name for synthetic rubbers made by polymerization of 2-chloro-1, 3-butadiene (prepared by the action of hydrogen chloride on monovinylacetylene).
Pinch valve constructions have been used in a wide variety of situations. More specifically, pinch valve constructions have been used in controlling the flow of, by way of example, solids in suspension (either in slurry or air-conveyed form), especially abrasive materials such as metallic ores, asbestos, fiber, sand, coal, sugar, wood chips or pulps, paper stock, plastic pellets, raw sewage, talc, cement, fly ash, as well as for conveyance of various fluent chemicals and foodstuffs.
In some situations where pinch valves are utilized, the material being conveyed through the conduit, duct, pipe, or tube in which the valve is interposed enters the valve sleeve under a great deal of pressure and it is desirable to reduce the flow pressure so that the material will flow into the pipe or conduit portion downstream of the valve at a lower pressure than upstream of the valve. Examples of situations where such a pressure differential between the portion of a pipe or conduit upstream of a pinch valve and those downstream of the valve are desirable are in the mining and chemical industries where materials are being conveyed in, for example, slurry form at high pressure and a means built into the pipeline or conduit system, which means is capable of reducing the line pressure with or without actuation by any separate mechanical or other arrangement, is required.
The pinch valve sleeves of the prior art are not useful for providing a reduction in pressure as described hereinabove because they are generally constructed in such a fashion that their inner surfaces, which bound the flow-through passage, are of a smooth configuration and, thus, the fluid passing through the sleeve is not impeded or interfered with in any fashion and exits from the outlet opening of the valve under the same pressure as it was under when it entered the valve. In order to decrease the pressure of the fluid flowing through the valve, the pinching means must be actuated to squeeze the valve sleeve and thus provide a smaller flow-through passage.
The applicant is not aware of prior art patents or publications relating to pinch valve sleeves with internal obstructions, but among the prior art patents relating to pinch valve constructions generally may be mentioned U.S. Pat. Nos. 2,167,952; 2,660,395; 3,588,034; and 4,172,580.